Winterfell
A Rust STARK prover/verifier library, originally released by Facebook/Novi. It handles the FRI protocol, polynomial commitments, and Merkle tree machinery; callers define an Air implementation describing their own transition and boundary constraints.
In this repo: the entire cryptographic engine underneath
zkvm-stark. One quirk worth knowing if you're using it too: its debug-only validate_transition_degrees self-check is stricter than actual soundness requires — see the reproduction and why release mode is correct here.